OXA-23-like, OXA-40-like, OXA-58-like and OXA-51-like carbapenemase gene PCR
|Lab name||Antibiotic Reference Laboratory|
|Lab location||Kenepuru Science Centre, Porirua|
|Test name||OXA-23-like, OXA-40-like, OXA-58-like and OXA-51-like carbapenemase gene PCR|
|Organisms||Acinetobacter and Pseudomonas|
|Requested for surveillance||no|
|Routine turnaround time||6 working days for reference specimens|
|Culture requirements||Pure culture|
|Media requirements||A slope of any medium that supports the growth of the organism|
|Pre-transport requirements||Ambient temperature|
|Transport requirements||Ambient temperature|
|Unacceptable sample types||Clinical specimens will not be accepted.|
|How results reported||The results will state whether OXA-23-like, OXA-40-like, OXA-58-like or OXA-51-like genes or the ISAba1 insertion sequence were detected|
Demonstration of the presence of an OXA carbapenemase gene by PCR.
Carbapenemase-mediated carbapenem resistance in Acinetobacter is most often due to the production of an OXA-23-like, OXA-40-like or OXA-58-like carbapenemase. In addition, carbapenem resistance in Acinetobacter may be due to overexpression of an OXA-51-like carbapenemase. OXA-51-like carbapenemases are intrinsic in A. baumannii and normally expressed at low levels but they can be overexpressed following the insertion of an ISAba1 sequence element upstream of the OXA-51 gene.
To check for the presence of OXA-23-like, OXA-40-like, OXA-58-like and OXA-51-like genes, a multiplex PCR is used and contains primers for each of the four groups of OXA-type carbapenemases. Any Acinetobacter isolates that are carbapenem resistant, but only positive for OXA-51-like genes in the multiplex PCR, are tested by PCR for the ISAba1 insertion sequence.
This test is appropriate for carbapenem-resistant Acinetobacter or Pseudomonas isolates.